It has been proposed in the art relating to diesel engines to obtain particulate emission control by the provision of an exhaust trap or filter in which particulates are collected with periodic incineration of the collected particulates. Various means have been proposed for igniting particulates collected in a trap at periodic intervals in order to obtain their incineration at desired intervals. Examples of such means include fuel burners incorporated in or ahead of the particulate trap, electric heating devices and throttling of the engine intake to increase the exhaust gas temperature. In general, such arrangements have required one or more additional heating units and/or relatively complex control systems to be added to the engine system.